1. Field of the Invention
The invention is related to the communications field, and in particular, to call processing systems and methods.
2. Description of the Prior Art
Mobile communications carriers typical handle calls connected from a mobile carrier network to destinations located on other networks such as the public switched telephone network (PSTN). To connect such a call destined for the PSTN, a mobile carrier routes the call from a mobile switch of their mobile network to a domestic switch of the PSTN. For example, the mobile carrier could route the call to a class 4 switch of the PSTN such as the DMS-250 offered by Nortel Networks, Inc.
During call setup, the mobile switch transmits call signaling to the domestic switch for call processing. The call signaling indicates the calling party number for the mobile phone which is used by the domestic switch to determine whether or not to connect the call and how to connect the call. For instance, the domestic switch might reject the call if the calling party number (CPN) indicates a customer that has delinquent bills. However, a problem arises when the CPN adheres to a format incompatible with a format recognized by the domestic switch therefore precluding the domestic switch from conducting call processing based on the CPN. For example, the DMS-250 class 4 switch recognizes CPNs that adhere to the North American Dialing Plan (NADP). If the CPN does not fit the NADP, the DMS-250 class 4 switch rejects the call.
Mobile carriers desire to provide international roaming services to customers, but these customers have calling party numbers that adhere to international formats and not the NADP. Thus, when the mobile carrier switch attempts to connect an international roaming call to the PSTN, the domestic switch of the PSTN does not recognize the international format of the calling party number and cannot conduct call processing based on the CPN. Lacking the ability to process the CPN, the domestic switch rejects the call.